In which of the following cases, the reaction goes farthest to completion?

Options

A. `K=10^(3)`
B. `K=10^(-2)`
C. `K=10`
D. `K=10^(0)`

Explanation

To determine in which case the reaction goes farthest to completion, we need to analyze the equilibrium constants (K) provided for each reaction. The reaction with the highest equilibrium constant will proceed the farthest toward completion.

### Step-by-Step Solution:

1. **Understanding Equilibrium Constant (K)**:
- The equilibrium constant (K) is a numerical value that indicates the ratio of the concentration of products to the concentration of reactants at equilibrium.
- A larger K value suggests that at equilibrium, the concentration of products is much greater than that of reactants, indicating that the reaction goes farthest toward completion.

2. **Comparing the Given K Values**:
- Let's list the given K values:
- Option A: \( K = 10^3 \)
- Option B: \( K = 10^{-2} \)
- Option C: \( K = 10 \)
- Option D: \( K = 10^0 \) (which is equal to 1)

3. **Identifying the Highest K Value**:
- Among the values:
- \( 10^3 \) (which is 1000) is the highest.
- \( 10^{-2} \) (which is 0.01) is the lowest.
- \( 10 \) (which is 10) is in the middle.
- \( 10^0 \) (which is 1) is also lower than \( 10^3 \).

4. **Conclusion**:
- Since \( K = 10^3 \) is the highest value, the reaction corresponding to this K value will go farthest to completion.
- Therefore, the correct answer is **Option A**.

### Final Answer:
**Option A** goes farthest to completion.